Как заставить дополнительную клавиатуру всегда работать в режиме цифр?

Code:

procedure TForm1.FormCreate(Sender: TObject);

begin

Application.OnMessage := AppOnMessage;

end;

procedure TForm1.AppOnMessage(var Msg: TMsg; var Handled: Boolean);

var ccode: Word;

begin

case Msg.Message of

   WM_KEYDOWN, WM_KEYUP:

   begin

     If (GetKeyState( VK_NUMLOCK ) >= 0)  //NumLock не включён

         and ((Msg.lparam and $1000000) = 0)

     then

     begin

       ccode := 0;

       case Msg.wparam of

         VK_HOME:  ccode := VK_NUMPAD7;

         VK_UP  :  ccode := VK_NUMPAD8;

         VK_PRIOR: ccode := VK_NUMPAD9;

         VK_LEFT:  ccode := VK_NUMPAD4;

         VK_CLEAR: ccode := VK_NUMPAD5;

         VK_RIGHT: ccode := VK_NUMPAD6;

         VK_END : ccode := VK_NUMPAD1;

         VK_DOWN : ccode := VK_NUMPAD2;

         VK_NEXT : ccode := VK_NUMPAD3;

         VK_INSERT:ccode := VK_NUMPAD0;

         VK_DELETE:ccode := VK_DECIMAL;

       end;

       If ccode <> 0 then Msg.Wparam := ccode;

     end;

   end;

end;

end;